Friday, 16 November 2007

Questions we should ask ourselves

As PhD students we should be clear about the advantages and disadvantages of specialization.

Is Specialization a Dead End?
The Phylogeny of Host Use in Dendroctonus Bark Beetles (Scolytidae)

Scott T. Kelley, Brian D. Farrell
Evolution, Volume 52, Issue 6 (Dec., 1998), 1731-1743.

The concept that specialization leads to an evolutionary dead end, first postulated by Cope (1896) as the "law of the unspecialized," has been a central idea in evolutionary biology
(Huxley 1942; Mayr 1963; Rensch 1980).
While shifts between generalist and specialist habits surely occur in both directions, it is not yet clear whether specialists are more often phylogenetically derived and dispersed (i.e., highly
"tippy"; found at the tips of the phylogenetic tree) consistent with the notion that specialists more often go extinct.

The "jack of all trades, master of none" hypothesis is commonly used to explain the prevalence of specialists (Via 1984, 1986; Simms and Rausher 1989; Tienderen 1991; Schluter 1995; Robinson et al. 1996). Under this hypothesis, specialization evolves as a consequence of trade-offs in performance of organisms on different hosts, such that optimized use of one host limits performance on others (Simms and Rausher 1989; Futuyma and Moreno 1988; Jaenike 1990).
Disparate results in the search for performance trade-offs has led to evaluation of other factors favoring specialization, such as freedom from natural enemies (Price et al. 1980; Bernays
and Graham 1988).

No comments: